Engine starter protective and control systems have been known heretofore. For example, in my prior U.S. Pat. No. 4,209,816, dated June 24, 1980, there is disclosed a protective control for vehicle starter and electrical systems having a number of desirable features. One of these features is a reverse polarity protection circuit operable such that if the battery is connected in reverse polarity, the starter system cannot be operated. Another of these features relates to automatic disengagement of the starting function when the engine reaches a predetermined "run" speed. This is accomplished by a frequency sensor that senses the frequency of a tachometer generator driven by the engine and disengages the starter when a frequency indicative of a predetermined run condition is reached during the starting operation. And another of these features relates to prevention of reengagement of the starter while the engine is running. This is accomplished in the aforementioned patent by applying hysteresis to the frequency sensor such that it cannot be reactivated to operate the starter until the engine speed has decreased to a very small value equivalent to an almost stopped condition. Also, my copending application Ser. No. 449,072, filed Dec. 13, 1982, discloses a dual voltage engine starter management system having a number of additional desirable features. A primary feature thereof is the use of two battery packs and contactors for connecting such battery packs in series mode for cold weather starting or in parallel mode for warm weather starting and a starter contactor that controls the starter motor circuit to protect the conventional starter solenoid contacts. Another feature thereof is the use of a single sequencing timer for controlling the contactors in particular sequences, both for high and low voltage start cycles and for starting and terminating start cycles. A further feature relates to a low voltage detector that controls a start-terminate latch means to abort the start cycle if the start motor voltage is too low for effective starting whereas a frequency sensor sets the latch to end the starting cycle when the engine reaches running speed. A further feature relates to a transfer detector that sets the latch to abort the starting cycle if mode transfer is attempted during the starting cycle. An additional feature relates to weld detectors that function at the end of the start cycle to prevent reclosing of the parallel contactor if the contacts of either the series contactor or a pilot relay that controls the conventional starting solenoid have failed to open.
While these prior systems have been useful for their intended purposes, this invention relates to improvements thereover.